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authorOdin Ugedal <odin@uged.al>2021-06-29 14:14:52 +0200
committerPeter Zijlstra <peterz@infradead.org>2021-07-02 15:58:24 +0200
commit72d0ad7cb5bad265adb2014dbe46c4ccb11afaba (patch)
tree93567a1879448c91711ed8ff217a59c039403767 /kernel
parentceb6ba45dc8074d2a1ec1117463dc94a20d4203d (diff)
sched/fair: Fix CFS bandwidth hrtimer expiry type
The time remaining until expiry of the refresh_timer can be negative. Casting the type to an unsigned 64-bit value will cause integer underflow, making the runtime_refresh_within return false instead of true. These situations are rare, but they do happen. This does not cause user-facing issues or errors; other than possibly unthrottling cfs_rq's using runtime from the previous period(s), making the CFS bandwidth enforcement less strict in those (special) situations. Signed-off-by: Odin Ugedal <odin@uged.al> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ben Segall <bsegall@google.com> Link: https://lore.kernel.org/r/20210629121452.18429-1-odin@uged.al
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/fair.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1e263c9cdc13..1b15a19910a3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5054,7 +5054,7 @@ static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
{
struct hrtimer *refresh_timer = &cfs_b->period_timer;
- u64 remaining;
+ s64 remaining;
/* if the call-back is running a quota refresh is already occurring */
if (hrtimer_callback_running(refresh_timer))
@@ -5062,7 +5062,7 @@ static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
/* is a quota refresh about to occur? */
remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
- if (remaining < min_expire)
+ if (remaining < (s64)min_expire)
return 1;
return 0;